1. Field of the Invention
This invention relates to a master information carrier for magnetic transfer provided on its surface with an embossed pattern (a pattern of protruding portions and recessed portions) representing information to be transferred to a slave medium such as a magnetic recording medium.
2. Description of the Related Art
As a method of recording a preformat signal such as a servo signal on a slave medium, there is known a magnetic transfer method in which a magnetization pattern representing the signal as an embossed pattern carried by a master information carrier is recorded on or transferred to a magnetic recording layer of the slave medium. See, for instance, U.S. Pat. Nos. 6,567,227, 6,636,371 and U.S. patent Laid-Open No. 20020051307.
In the magnetic transfer, a magnetization pattern representing the information carried by a master information carrier in the form of a fine embossed pattern is magnetically transferred from the master information carrier to a slave medium by applying a transfer magnetic field to the slave medium and the master information carrier in close contact with each other, and accordingly, the information carried by the master information carrier can be statically recorded on the slave medium with the relative position between the master information carrier and the slave medium kept constant. Thus, according to the magnetic transfer, the preformat recording can be performed accurately and the time required for the preformat recording is very short.
The conventional magnetic transfer is developed based on that the shortest bit length is 500 nm to 1 μm. However recent rapid increase in recording density in magnetic recording media, especially in hard disks, further shortens the shortest bit length to the order equal to or less than 100 nm. The shortest bit length in servo signals is normally as long as two to three times that in data areas. Nevertheless, it comes to be necessary to discuss suitability of transfer of the pattern including a bit length on the order of 300 nm or shorter.